No, a router is not only for Wi-Fi. Routers can be used to connect devices to a network using wired connections as well. In fact, many routers have both wired and wireless ports, so you can choose which type of connection is best for your needs.
If you need to connect devices that are far away from the router, such as a printer or a game console, you will need to use a wired connection. Wired connections are also typically faster than wireless connections, so if you need the fastest possible speeds, you should use a wired connection.
However, if you want the flexibility to move around your home or office without being tethered to a cable, you can use a wireless connection. Wireless connections are also convenient for devices that you don’t use very often, such as a guest’s laptop or a smart TV.
So, while routers are often used to create Wi-Fi networks, they can also be used to connect devices to a network using wired connections. The best type of connection for you will depend on your specific needs and requirements.